Hydrocarbon conversion



lg- 19, l941- R. F.'MAR$CHNER .l 2,252,928

HYDROGARBON CONVERSIQN Filed mig. 1o, 193s 4 ANN 55mg www y PatentedAug. 19, ,1941

UNITED .STATES APll'riazNT OFFICE I azsaszs maooAaBoN ooiwvnaslorryRobert F. Marschner, Chicago, Ill.,Y asslgnor to. Standard Oil Company,Chicago, Ill., a corporation of Indiana Application August 10, 1939,Serial No. 289,364

9 Claims.

This invention relates to an improved process for the conversion ofhydrocarbon materials into motor fuels characterized by high octanenumbers. More particularly, it relates to an improved process for theproduction of high octane number gasoline containing hydrocarbon aminesproduced in situ. The invention also relates'to an improved process forproducing aromaticy amines, such as aniline, from the saturated cyclichydrocarbons present in petroleum naphthas It .is an object of thisinvention .to provide'an improved process forthe conversion ofhydrocarbons into high octane number gasolines. Another object is toprovide a process vwhereby a low octane number hydrocarbon feed stockcontaining naphthenes is converted into a high antiknock gasoline.- Itis a still 'further 'object of my invention to provide a method andmeans for nitrating hydrocarbon feed stock and converting nitrohydrocarbons into hydrocarbon amines simultaneously with dehydrogenationof the hydrocarbon material. Anotherl object of this lnvention is toprovide a process for the conversion of saturated cyclichydrocarbonsinto aromatic amines. Other objects and advantages will be- .comeapparent as the description of this invention proceeds. v

I have' discovered that nitrated naphtha need not contain aromatic.hydrocarbons in order to produce aromatic airlines in a subsequentreducing step. In brief, the present application is Y concerned with aprocess'in which saturated cy- 'clic hydrocarbons present in petroleumnaphcyclohexanes and oxidation products, it is passed over a catalyst ofthe dehydrogenation type. The reaction product from this step, after theremoval of unreacted hydrocarbons. and the separation of the waterproduced, consists mainly of aniline and its homologues. Detectableamounts ofbther products such as benzene, phenol, di-

' stock enters through line I0. A suitable hydrophenylamlne andunidentified substances are often also formed. While such products areval- I Auable chemical compounds, it is desired to obtain as large ayield of aniline and hence as little of these-various other products aspossible. The aniline is useful in raising the octane number of naphthasand because of its relatively high boiling 'point (363 F.) lsparticularly valuable in increasing the octane number of the heavierfrac- 10 tions of thenaphtha, such as those boiling between 320 and 392F., which usually show a low octane number, sometimes below zero. Ineffect, the present process converts cyclohexane which is 'present inthe lighter high-octane number fractions to aniline-which markedlyraises the octane number-of the heavier low-octane number fractions. Useof higher cyclohexane hydrocarbons such as those containing 9 .to 11carbon atoms tend to give aromatic amines which boil above the gasolinerange.

V Because of their large antiknock eect, perF missible. quantitiesof'aromatic amines are desirable in ordinary gasoline, but it is alsocontemplated to remove the gasoline by distillation and to add theresidual amine mixture to a naphtha having an initial boiling point of350 F. or to a synthetic hydroc-arbon mixture to produce a very highoctane number safety fuel.

In employing my process to increase the octane number of a typical motorfuel, the simple process of nitrating and dehydrogenating a n, naphthawithout intermediate distillation or final close fractionation ispermissible. Because the feed need not contain aromatic hydrocarbons. a

wide variety of poor octane number stocks may be charged.

-The accompanying drawing is a ilow diagram which illustratesschematically one method for carrying out my process.

Referring now to the drawing, a naphtha feed carbon feed stock may beobtainedby the distillation'oi crude oils to obtain a cut boilingbetween 100 F. and 300 F. These are ordinarily referred to asstraight-run or virgin naphthas and. will contain varying amounts ofparailins, aromatics and naphthenes. Since the aromatic constituentspossess a "high octane number and a high blending value when mixed withhydrocarbon mixture of low antiknock characteristics, it is desirable tocarry out the4 process on,an aromatic-free stock. Moreover, I

prefer to use a naphthene-rich naphtha such as 'the naphthasfromCoastal, South American or lEuropean crudes and from certainMid-Continent crudes.

In order to remove the greater part of the aro-- matics which may bepresent the -naphtha from line IIIl is directed through valved line. IIto a l solvent extraction tower I2 wherein it is contacted with asolvent having an ailinity for the aromatic hydrocarbons. Suitablesolvents include sulfur dioxide.- iuriural, aluminumchloride-hydrocarbon complex, etc. lFor purposes 'of' illustration theprocess will be described yrelative to a sulfur dioxide extractionprocess. The

solvent enters through line I3 and is thoroughly :i9 to blending tank 20or may be withdrawn from the system through valved line 2I..

'I'he aromatic-free naphtha plus some solvent passes overheadthroughline 22'to raiiinate stripper 23. Heating means 24 therein aidsin stripv -The nitrated hydrocarbons plus excess hydrocarbons passoverhead throughline II to separator $2.` A condenser 33 may beinterposed in line SI to reduce the'temperature of the reactants priorto separation. In separator 32 water separates from the solution ofnitro-hydrocarbons and excess hydrocarbons, and may be withdrawn throughline N. At high rates of iiow through the reactor,` some of the nitricacid may remain unchanged, and it may be desirable to recycle themixture together with the water formed to ni' trators 21 through valvedline Il which joins line 29. Ii the'nitrating agent has been dilutedA bythe formation of toogreat an amount ofwater, it may be withdrawn'throughvalved line Il and reconcentrated or discarded as desired. Partiallynitrated naphtha may also be recycled through the nitrator (by means notshown) ,but because ping the sulfur dioxide from the naphtha, the

solvent passing overhead through line 24 and returning to the solventextraction system through line I3. The aromatic-free naphtha iswithdrawn through line 26 and directed to a nitration reactor 2l throughline 28. A nitrating agent is added to nitrator 2'I through line 29.

In nitrator 21 the hydrocarbon feed stock is incompletely converted intonitro-hydrocarbons. Traces of aromatichydrocarbons, if present, willusually nitrate completely. Since there are preferably large amounts ofnaphthenes present these will nitrate in preference to the parailinichydrocarbons. The nitration can be carried out in any one of a number ofdifferent ways. For example, -a mixture of concentrated sulfuric acidand concentrated nitric acid may be employed? the temperature beingmaintained sumciently low, as by means of cooling jacket 3,to avoid theformation of dinitro. compounds or yoxidation products. Nitration mayalso be carried out by means of aluminum nitrate or ferric nitrate. Itis preferable, however, to carry out the reaction in the vapor phasewith nitric acid alone, since the higher temperature employed appears togivev a more selective nitration of naphthenes. f

The reactor may consist of a simple coil or o! a packed vessel, butinany event is mounted in a bath or other suitable device which not onlymay be maintained at the desired temperature, but also serves to absorbheat from the exothermic nitration reaction. The packing may consistvofany suitable inert material, such as that o! which the container isconstructed, but preferably in ilnely divided, granular,` porous,acicular or spatulate form. This serves the multiple purpose of creatingturbulent now, Diovidin'g an increased adsorptive surface, and assistingin maintaining temperature control. The particular manner of nitratingthe hydrocarbon material is not essential to my invention, any knownmeans for accomplishing this-result may be used. For example, nitrationcan be carried lout according to the method of Hopkins in U. S. 4Patent1,558,027

in which aluminum nitrate and. nitric acid act as the nitrating agents,the reaction being carried out at approximately 265 -to about 300 Pf.

'65 head through line Il and the hydrocarbons heavier than those desiredfor gasoline or blemi-` this usuaily leads to the formation oiundesirable oxidation products this vmethod o! operation is often notdesirable. l

The solution o1 nitro-hydrocarbons in naphtha pass overhead fromseparator 21 and is heated in furnace 3l. The heated hydrocarbons leaveiurnace 38 through line I9 and are directed to dehydrogenatorl. Thedehydrogenatlon is carried out preferably by catalytic means. Thecatalyst may comprise metallic chromites, particularly magnesiumchromite, chromium oxide gels, mixtures oi aluminum `oxide and chromiumoxide, chroinic oxide supported upon preformed alumina, supportedmolybdenum oxide, ceria, and vanadia. Tungstic oxide and uranio. arealso satisfactory catalysts when supported in relatively small amountsupon alumina and other supports.

The nitrated hydrocarbons are contacted with the catalyst at atemperature of about '750 to 900 F. and preferable1 at about 850 F. atlow pressure, i. e., atmospheric to about 50 pounds per square inch witha space velocity of about 0.5 to 3 volumes (liquid basis) preferablyabout i volume, of nitrated naphtha per volume of catalystspace perhour. The catalyst may be employed in nxed beds, in movable beds or as apowder suspended in the gaseous stream, the conversion in all caseswithdrawn through line II and directed to frac-' tionator 42 throughvalved line Il. Water can either be removed in a separator beforeiractionator 42, or from a separator 44 in line 4l'.

` In iractionator 42 the hydrocarbons and hydrocarbon amines ot thedesired boiling range are withdrawn through line Il. The hydrogen andnormally gaseous hydrocarbons are taken overing purposes are withdrawnthrough line El.

Water is separated from the product in separator M and withdrawn throughline, the hydrocarbons and hydrocarbon amines beingwithdrawn throughline 4s. The octane number of the gasoline withdrawn; through line d!wili depend to a large degree on the extent of the nitration of thehydrocarbon feed stock. V l t Simultaneously, dei lniline or itsderivatives which will constitute drawn through valved line 50 and usedas such for gasoline. If the nitration has been carried to such anextent that the product has an octane numbervmuch above that foundsuccessful for commercial gasolines, it may be `withdrawn through valvedline and directed to blending tank wherein it may b e blended with a lowantiknock stock, `such as, for example, another portion of the originalstock used.l This may be added to blending'tank 20`throughvalved line 52which joins line 53. A low antiknock stock from.extraneous sources maybe added to line 53 through line 54, I-t is also possible to add throughline 55 tetraethyllead or other antiknock agent in order to increasefurther the octane number of the'low octane stock, the amount oftetraethyl lead in the stock conforming to customary optimumconcentrations. As an advantage of the present processit may benoted'that the effect of aniline upon -sensitive fuels'such as crackedgasoltne containing olens or extracts containing aromatics does notdepreciate to as great a degree as does that oftetraethyl lead. 'Iheblended gasoline can be withdrawn through line 51.

I contemplate the removal 'of aniline and its .homologues from theproduct when the feed contains a large portion of cyclohexanehydrocarbons and homologues thereof. 'I'his is readily accomplished by avariety of methods. For example. they may be extracted with an aqueoussolution of an acid such as hydrochloric acid, or with an inert solventsuch as ammonia, or with organic solvents such as phenol. The extractmay be then fractionated to give pure aniline. toluidine, xylidene,etc., which may be employed as dye intermediates, etc. For example, themixture of hydrocarbons and hydrocarbon amines may be directed from line49 through valved line 58 to extractor 59. A suitable solvent is addedthrough line 60 and the unconverted hydrocarbons withdrawn overheadthrough `line 6l..,If necessary, the product from line 6| may be pu"ified by Water WaShing,.etc. by means not shown, to remove traces ofsolvent. The solvent containing the hydrocarbon amines is withdrawn.

through line 62 and directed to fractionator 63 wherein'the solvent andthe hydrocarbon amines are separated, the solvent free amines beingwithdrawn through line 64 for use in blending. or as a dye intermediate,etc. I'he solvent is withdrawn through line 65, and discarded orreturned to extractor 59.

I also contemplate nitration of relatively pure cyclohexane, or thenitration of mixtures con'- V y taining cyclohexan'e, and isolatingrelatively pure nitrocyelohexane, subsequently dehydrogenating thedehydrogenation of saturated hydrocarbons is undeslrabie. In this event,the 'napntna win be process since they themselves are valuable for.

their high antiknock qualities.` Moreover, the aromatic hydrocarbonsnitrate in preference to the cycloparaiilns and the paramnic stocks sothat in order to convert these latter hydrocarbons it is necessary tocarry out the nitration to a much greater .extent than would otherwisebe necessary.

Generally speaking, the aromatics have avery much higher octane numberrating and a much g higher blending octane number than the correspondingcyclo-paraffins; therefore, it is my desire to increase the octanenumber of the cycloparamns and omit, if possible, the conversion of thearomatics. The aromatics as has been pointed out, may be blended withthe converted hyv drocarbons or may be utilized for purposes other thanmotor fuels such as, for instance, high solvency naphthas, the formationof dyestuffs, etc. By my process a hydrocarbon feed stock of low octanenumber may be converted to a high octane number motor fuel or may beconverted to a blending stock for increasing the octane number of anoverall mixture of unconverted low octane number stock and thedehydrogenation product.

My process is particularly advantageous in that by utilizing in situ thehydrogen formed during the dehydrogenation process an active hydrogenfor reducing nitrohydrocarbons to amines is immediately available and,at the same time, the formation of additional unsaturated hydrocarbonsis promoted by the removal of hydrogen from vthe process. Under ordinarycircumstances limited by thel amount of hydrogen present since under theconditions of operation it is possible also to hydrogenate theunsaturated hydrocarbons formed, in a reversible reaction, and an equi..librium is set up. By removing the hydrogen through the formation ofhydrocarbon amines from nitro-hydrocarbons 'the saturated-unsaturatedhydrocarbon equilibrium ls thrown in the direction of greater amounts ofunsaturated hydrocarbons. The unsaturated content and thus the octanenumber due to hydrocarbons alone is consequently appreciably increased,while in addition, the formation of an antidetonating agent is `carriedout in situ.

I claim:

1. A process for theproduction of a high antiknock fuel from a lowantiknock fuel containing a substantial amount of naphthenichydrocarbons which comprises nitrating at least a portion of thenaphthenic hydrocarbons in said low antiknock fuel and subjecting theproduct from said nitratlon to catalytic dehydrogenation to reduce theproduct to aniline. Similarly, homologues of cyclohexane, after such alogues of aniline.

Although I have illustrated 4the solvent extraetion of aromatics fromthe feed stock it is quite possible that the amount of aromatics in thehydrocarbon-mixture is sufficiently low so that the solvent extractionstep becomes economically process, will give homothe naphthenichydrocarbons to aromatic amines in an amount sufficient to increasesubstantially the antiknock value of said low antiknock fuel.

2. A process for the production of a high antiknock motor fuel from alow .antiknock motor fuel containing a substantial amount of naphthenichydrocarbons which comprises nitrating at least a portion of saidnaphthenic hydrocarbons in said low antiknock motor fuel to formnitro-naphthenes, catalytically dehydrogenating the unnitratedhydrocarbons in said low antiknock motor fuel and simultaneously subjeting said nitro-naphthenes to said catalytic dehydrogenation to reducethe nitro-naphthenes tn aromaticamines in an amount sumcient to increasesubstantially the antiknock value of said low antiknock motor fuel.

3. A process for the production of a high antiknock motor fuelcomprising, nitrating a naphtha containing a substantial amountofnaphthenic hydrocarbons, said naphtha being substantially free ofaromatic hydrocarbons, and catalytically dehydrogenating said nitratednaphtha to reduce the nitro-hydrocarbons to organic amines in an amountsumcient to increase substantially the antiknock value of sa'id naphtha.

4. A process for the production of a high antiknock motor fuelcomprising, subjecting a suba stantially aromatic-free naphthacontaining cyclohexane to nitration, -and dehydrogenating said nitratednaphtha while simultaneously `converting said nitrated naphtha toorganic airlines in an amount suillcient to increase substantially `theantiknock value of said aromatic-free naphtha. Y

5. In a process for the production of a high antiknock motor fuel. thesteps comprising removing substantialiy all aromatic hydrocarbons from apetroleum naphtha containing a substantial amount of saturated cyclichydrocarbons,

" nitrating said cyclic hydrocarbons contained in aromatic-free naphthato form nitro-hydrocarbons, and subjecting said aromatic-free naphthacontaining said nitro-hydrocarbons to catalytic dehydrogenation whereinaromatic Vamines are formed in an amount sumcie'nt to increasesubstantially the antiknock value of said petroleum naphtha.

6. In a process for the production of a high antiknock motor fuel, thesteps comprising removing substantially all aromatic hydrocarbons fromalpetroleum naphtha containing a substan.-

tial amount of saturated cyclic hydrocarbons, nitrating said saturatedcyclic hydrocarbons in said aromatic-free naphtha to formnitro-hydrocarbons, subjecting said aromatic-free naphtha containingsaid nitro-hydrocarbons to catalytic dehydrogenation whereby aromaticamines are formed in an amount suicient to increase substantially theantiknock value of said petroleuxn naphtha and blending said naphthacontaining aromatic amines-with a low octane numbernaphtha. j o

'1. In a process for the production of a high antiknock motor fuel. thesteps comprising removing substantially all aromatic hydrocarbons from apetroleum naphthacontaining av substantial 'amount dft'saturated cyclichydrocarbons,

-nitrating said saturated cyclic hydrocarbons and said aromatic-freenaphtha to form nitro-hydrocarbons, subjecting saidaromatic-free naphthaingV said saturated cyclic hydrocarbons andV aromatic-free naphtha toform nitro-hydrocarbons, subjecting said laromatic-free naphthacontaining said nitro-hydrocarbons to catalytic dehydrogenation whereinaromatic amines are formed, separating said aromatic amines from saidnaphtha, and blending said aromatic amines with a heavy low .antiknockgasoline to form a safety aviation fuel of high octane number.

9. In a', process for the production of a. high y 'antiknock motor fuel,the steps comprising removing substantially all aromatic hydrocarbons efrom a petroleum naphtha containing a substantialamount vof saturatedcyclic hydrocarbons.

nitrating said cyclic hydrocarbons contained in said aromatic-freenaphtha to form nitro-hydrocarbons, subjecting said aromatic-freenaphtha containing said nitro-hydrocarbons to catalytic `dehydrogenationwherein aromatic amines are formed in an amount suillcient to increasesubstantially the antiknock value of said petroleum naphtha, andblending said removed aromatic hydrocarbons with said petroleum naphthaof increased antiknock value to form an improved motor fuel. Y

ROBERT F. MARSCHNER.

